scholarly journals Mineralogical and morphological properties of individual dust particles in ice cores from the Tibetan Plateau

2016 ◽  
Vol 62 (231) ◽  
pp. 46-53 ◽  
Author(s):  
GUANGJIAN WU ◽  
XUELEI ZHANG ◽  
CHENGLONG ZHANG ◽  
TIANLI XU
Keyword(s):  
Tibetan Plateau ◽  
Aspect Ratio ◽  
Morphological Characteristics ◽  
Ice Cores ◽  
Morphological Properties ◽  
Dust Particles ◽  
The Tibetan Plateau ◽  
Ratio Distribution ◽  
Northern Tibetan Plateau ◽  
The Individual

ABSTRACTUsing a field emission scanning electron microscope and energy-dispersive X-ray spectrometer (FESEM−EDS), individual insoluble dust particles in ice cores recovered from the northern (Dunde), western (Muztagata) and south-eastern (Palong-Zangbo) Tibetan Plateau were analysed in order to reveal the mineralogical and morphological characteristics of the analogue of long-range transported Asian dust. The results reveal that the dust particles are mainly composed of quartz (17–36%, number abundance), clay (37–48%) and feldspar (12–18%). Illite and chlorite are the dominant clay species, while kaolinite is rarely observed. For the three sites, regional differences in the mineral assemblages are significant, in particular the abundance of quartz, chlorite and muscovite species, reflecting the regional provenance of these dust particles and the climatic regime in their source areas. Oxide ratios in clays indicate different weathering strengths of the particles in their source regions, with a higher K2O/(SiO2 + Al2O3) in the western and northern Tibetan Plateau. The individual particles have modes of 1.48 and 1.53 in the aspect ratio and circularity distribution respectively. No significant relationship between aspect ratio and circularity was found. Quartz and feldspar particles have a narrow aspect ratio distribution. Muscovite particles have the coarsest grain size, while chlorite particles have the finest.

scholarly journals The visible spectroscopy of iron oxide minerals in dust particles from ice cores on the Tibetan Plateau

Tellus B ◽  
2016 ◽  
Vol 68 (1) ◽  
pp. 29191 ◽  
Author(s):  
Guangjian Wu ◽  
Tianli Xu ◽  
Xuelei Zhang ◽  
Chenglong Zhang ◽  
Ni Yan
Keyword(s):  
Iron Oxide ◽  
Tibetan Plateau ◽  
Ice Cores ◽  
Dust Particles ◽  
The Tibetan Plateau ◽  
Visible Spectroscopy ◽  
Oxide Minerals

scholarly journals Temperature variations over the past millennium on the Tibetan Plateau revealed by four ice cores

2007 ◽  
Vol 46 ◽  
pp. 362-366 ◽  
Author(s):  
Tandong Yao ◽  
Keqin Duan ◽  
L.G. Thompson ◽  
Ninglian Wang ◽  
Lide Tian ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
19Th Century ◽  
Northern Hemisphere ◽  
Ice Core ◽  
Ice Cores ◽  
Ice Age ◽  
The Tibetan Plateau ◽  
Late 19Th Century ◽  
The Past ◽  
Northern Tibetan Plateau

AbstractTemperature variation on the Tibetan Plateau over the last 1000 years has been inferred using a composite δ18O record from four ice cores. Data from a new ice core recovered from the Puruogangri ice field in the central Tibetan Plateau are combined with those from three other cores (Dunde, Guliya and Dasuopu) recovered previously. The ice-core δ18O composite record indicates that the temperature change on the whole Tibetan Plateau is similar to that in the Northern Hemisphere on multi-decadal timescales except that there is no decreasing trend from AD 1000 to the late 19th century. The δ18O composite record from the northern Tibetan Plateau, however, indicates a cooling trend from AD 1000 to the late 19th century, which is more consistent with the Northern Hemisphere temperature reconstruction. The δ18O composite record reveals the existence of the Medieval Warm Period and the Little Ice Age (LIA) on the Tibetan Plateau. However, on the Tibetan Plateau the LIA is not the coldest period during the last millennium as in other regions in the Northern Hemisphere. The present study indicates that the 20th-century warming on the Tibetan Plateau is abrupt, and is warmer than at any time during the past 1000 years.

scholarly journals Volume-size distribution of microparticles in ice cores from the Tibetan Plateau

2009 ◽  
Vol 55 (193) ◽  
pp. 859-868 ◽  
Author(s):  
Guangjian Wu ◽  
Tandong Yao ◽  
Baiqing Xu ◽  
Lide Tian ◽  
Chenglong Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Normal Distribution ◽  
Ice Cores ◽  
Normal Function ◽  
Dust Particles ◽  
Volume Distribution ◽  
The Tibetan Plateau ◽  
Log Normal ◽  
Log Normal Distribution ◽  
Volume Size

AbstractThe volume distribution of atmospheric dust particles (microparticles) of 1–30 μm diameter in Muztagata, Dunde, Dasuopu and Everest ice cores from the Tibetan Plateau was measured and fitted as a log-normal function in order to characterize their basic size properties. Our results reveal that whether the volume distribution fits the log-normal function or not largely depends on the dust concentration and the specific dust-storm event but is independent of physiographical location and season. Our results show only high-concentration samples obey the log-normal distribution in volume, with mode sizes ranging from 3 to 161 μm. The log-normal distribution was largely attributed to the mid-sized particles between 3 and 15 μm, which contribute most (>70%) of the total volume. The volume size distribution characteristics for mineral dust particles from ice cores reveal that the coarse particles might be common in the upper-level troposphere over the Tibetan Plateau. These dust size features are useful to advance our understanding of dust effects on climate, and provide clues to better characterize atmospheric dynamics over the Tibetan Plateau that will help to improve the current models.

scholarly journals Surface ozone at Nam Co (4730 m a.s.l.) in the inland Tibetan Plateau: variation, synthesis comparison and regional representativeness

2017 ◽  
Author(s):  
Xiufeng Yin ◽  
Shichang Kang ◽  
Benjamin de Foy ◽  
Zhiyuan Cong ◽  
Jiali Luo ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Surface Ozone ◽  
Early Morning ◽  
Photochemical Reactions ◽  
Transport Processes ◽  
The Tibetan Plateau ◽  
Nam Co ◽  
Mixing Ratios ◽  
Northern Tibetan Plateau ◽  
Ozone Levels

Abstract. Ozone is an important pollutant and greenhouse gas, and tropospheric ozone variations are generally associated with both natural and anthropogenic processes. As one of the most pristine and inaccessible regions in the world, the Tibetan Plateau has been considered as an ideal region for studying processes of the background atmosphere. Due to the vast area of the Tibetan Plateau, sites in the southern, northern and central regions exhibit different patterns of variation in surface ozone. Here, we present long-term measurements for ~ 5 years (January 2011 to October 2015) of surface ozone mixing ratios at Nam Co Station, which is a regional background site in the inland Tibetan Plateau. An average surface ozone mixing ratio of 47.6 ± 11.6 ppb was recorded, and a large annual cycle was observed with maximum ozone mixing ratios in the spring and minimum ratios during the winter. The diurnal cycle is characterized by a minimum in the early morning and a maximum in the late afternoon. Nam Co Station represents a background region where surface ozone receives negligible local anthropogenic emissions. Surface ozone at Nam Co Station is mainly dominated by natural processes involving photochemical reactions and potential local vertical mixing. Model results indicate that the study site is affected by the surrounding areas in different seasons and that air masses from the northern Tibetan Plateau lead to increased ozone levels in the summer. In contrast to the surface ozone levels at the edges of the Tibetan Plateau, those at Nam Co Station are less affected by stratospheric intrusions and human activities which makes Nam Co Station representative of vast background areas in the central Tibetan Plateau. By comparing measurements at Nam Co Station with those from other sites in the Tibetan Plateau and beyond, we aim to expand the understanding of ozone cycles and transport processes over the Tibetan Plateau. This work may provide a reference for model simulations in the future.

scholarly journals Significant recent warming over the northern Tibetan Plateau from ice core <i>δ</i><sup>18</sup>O records

2016 ◽  
Vol 12 (2) ◽  
pp. 201-211 ◽  
Author(s):  
W. An ◽  
S. Hou ◽  
W. Zhang ◽  
Y. Wang ◽  
Y. Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Ice Core ◽  
Ice Cores ◽  
Global Temperature ◽  
Temperature History ◽  
Temperature Record ◽  
Northern Tibetan Plateau ◽  
Recent Warming ◽  
Warming Hiatus ◽  
Instrumental Records

Abstract. Stable oxygen isotopic records in ice cores provide valuable information about past temperature, especially for regions with scarce instrumental measurements. This paper presents the δ18O result of an ice core drilled to bedrock from Mt. Zangser Kangri (ZK), a remote area on the northern Tibetan Plateau (TP). We reconstructed the temperature series for 1951–2008 from the δ18O records. In addition, we combined the ZK δ18O records with those from three other ice cores in the northern TP (Muztagata, Puruogangri, and Geladaindong) to reconstruct a regional temperature history for the period 1951–2002 (RTNTP). The RTNTP showed significant warming at 0.51 ± 0.07 °C (10 yr)−1 since 1970, a higher rate than the trend of instrumental records of the northern TP (0.43 ± 0.08 °C (10 yr)−1) and the global temperature trend (0.27 ± 0.03°C (10 yr)−1) at the same time. In addition, the ZK temperature record, with extra length until 2008, seems to suggest that the rapid elevation-dependent warming continued for this region during the last decade, when the mean global temperature showed very little change. This could provide insights into the behavior of the recent warming hiatus at higher elevations, where instrumental climate records are lacking.

scholarly journals Diachronous Tibetan Plateau landscape evolution derived from lava field geomorphology

2020 ◽  
Author(s):  
Mark Allen ◽  
Robert Law
Keyword(s):  
Tibetan Plateau ◽  
Landscape Evolution ◽  
Tectonic Geomorphology ◽  
Normal Faults ◽  
The Tibetan Plateau ◽  
Lava Field ◽  
Northern Tibetan Plateau ◽  
Tectonic Processes ◽  
Stepwise Evolution

&lt;p&gt;&lt;strong&gt;Evolution of the Tibetan Plateau is important for understanding continental tectonics because of its exceptional elevation (~5 km above sea level) and crustal thickness (~70 km). Patterns of long-term landscape evolution can constrain tectonic processes, but have been hard to quantify, in contrast to established datasets for strain, exhumation and paleo-elevation. This study analyses the relief of the bases and tops of 17 Cenozoic lava fields on the central and northern Tibetan Plateau. Analyzed fields have typical lateral dimensions of 10s of km, and so have an appropriate scale for interpreting tectonic geomorphology. Fourteen of the fields have not been deformed since eruption. One field is cut by normal faults; two others are gently folded with limb dips &lt;6&lt;sup&gt;o&lt;/sup&gt;&lt;/strong&gt;&lt;strong&gt;. &lt;/strong&gt;&lt;strong&gt;Relief of the bases and tops of the fields is comparable to modern, internally-drained, parts of the plateau, and distinctly lower than externally-drained regions. The lavas preserve a record of underlying low relief bedrock landscapes at the time they were erupted, which have undergone little change since. There is an overlap in each area between younger published low-temperature thermochronology ages and the oldest eruption in each area, here interpreted as the transition &lt;/strong&gt;&lt;strong&gt;between the end of significant (&gt;3 km) exhumation and plateau landscape development. &lt;/strong&gt;&lt;strong&gt;This diachronous process took place between ~32.5&lt;sup&gt;o&lt;/sup&gt; - ~36.5&lt;sup&gt;o&lt;/sup&gt; N between ~40 and ~10 Ma, advancing northwards at a long-term rate of ~15 km/Myr. Results are consistent with incremental northwards growth of the plateau, rather than a stepwise evolution or synchronous uplift.&lt;/strong&gt;&lt;/p&gt;

scholarly journals Developing a novel hybrid model for the estimation of surface 8 h ozone (O<sub>3</sub>) across the remote Tibetan Plateau during 2005–2018

2020 ◽  
Vol 20 (10) ◽  
pp. 6159-6175 ◽  
Author(s):  
Rui Li ◽  
Yilong Zhao ◽  
Wenhui Zhou ◽  
Ya Meng ◽  
Ziyu Zhang ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Hybrid Model ◽  
Additive Model ◽  
World Health ◽  
The Tibetan Plateau ◽  
The Novel ◽  
Slow Increase ◽  
Potential Health ◽  
Generalised Additive Model ◽  
Northern Tibetan Plateau

Abstract. We developed a two-stage model called the random-forest–generalised additive model (RF–GAM), based on satellite data, meteorological factors, and other geographical covariates, to predict the surface 8 h O3 concentrations across the remote Tibetan Plateau. The 10-fold cross-validation result suggested that RF–GAM showed excellent performance, with the highest R2 value (0.76) and lowest root-mean-square error (RMSE) (14.41 µg m−3), compared with other seven machine-learning models. The predictive performance of RF–GAM showed significant seasonal discrepancy, with the highest R2 value observed in summer (0.74), followed by winter (0.69) and autumn (0.67), and the lowest one in spring (0.64). Additionally, the unlearning ground-observed O3 data collected from open-access websites were applied to test the transferring ability of the novel model and confirmed that the model was robust in predicting the surface 8 h O3 concentration during other periods (R2=0.67, RMSE = 25.68 µg m−3). RF–GAM was then used to predict the daily 8 h O3 level over the Tibetan Plateau during 2005–2018 for the first time. It was found that the estimated O3 concentration displayed a slow increase, from 64.74±8.30 µg m−3 to 66.45±8.67 µg m−3 from 2005 to 2015, whereas it decreased from the peak to 65.87±8.52 µg m−3 during 2015–2018. Besides this, the estimated 8 h O3 concentrations exhibited notable spatial variation, with the highest values in some cities of the northern Tibetan Plateau, such as Huangnan (73.48±4.53 µg m−3) and Hainan (72.24±5.34 µg m−3), followed by the cities in the central region, including Lhasa (65.99±7.24 µg m−3) and Shigatse (65.15±6.14 µg m−3), and the lowest O3 concentration occurred in a city of the southeastern Tibetan Plateau called Aba (55.17±12.77 µg m−3). Based on the 8 h O3 critical value (100 µg m−3) provided by the World Health Organization (WHO), we further estimated the annual mean nonattainment days over the Tibetan Plateau. It should be noted that most of the cities on the Tibetan Plateau had excellent air quality, while several cities (e.g. Huangnan, Haidong, and Guoluo) still suffered from more than 40 nonattainment days each year, which should be given more attention in order to alleviate local O3 pollution. The results shown herein confirm that the novel hybrid model improves the prediction accuracy and can be applied to assess the potential health risk, particularly in remote regions with few monitoring sites.

scholarly journals Precipitation record since AD 1600 from ice cores on the central Tibetan Plateau

2008 ◽  
Vol 4 (3) ◽  
pp. 175-180 ◽  
Author(s):  
T. Yao ◽  
K. Duan ◽  
B. Xu ◽  
N. Wang ◽  
X. Guo ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Ice Core ◽  
Ice Cores ◽  
The North ◽  
Northern Tibetan Plateau ◽  
Central Tibetan Plateau ◽  
Precipitation Record ◽  
Ice Field ◽  
The 19Th Century

Abstract. Lack of reliable long-term precipitation record from the northern Tibetan Plateau has constrained our understanding of precipitation variations in this region. We drilled an ice core on the Puruogangri Ice Field in the central Tibetan Plateau in 2000 to reveal the precipitation variations. The well dated part of the core extends back to AD 1600, allowing us to construct a 400-year annual accumulation record. This record shows that the central Tibetan plateau experienced a drier period with an average annual precipitation of ~300 mm in the 19th century, compared to ~450 mm in the wetter periods during 1700–1780 and the 20th century. This pattern agrees with precipitation reconstructions from the Dunde and Guliya ice cores on the northern Plateau but differs from that found in the Dasuopu ice cores from the southern Plateau The north-south contrasts in precipitation reconstruction reveals difference in moisture origin between the south Tibetan Plateau dominated by the Asian monsoon and the north Tibetan Plateau dominated by the continental recycling and the westerlies.

scholarly journals Characteristics and sources of dissolved organic matter in a glacier in the northern Tibetan Plateau: differences between different snow categories

2018 ◽  
Vol 59 (77) ◽  
pp. 31-40 ◽  
Author(s):  
Lin Feng ◽  
Yanqing An ◽  
Jianzhong Xu ◽  
Shichang Kang
Keyword(s):  
Organic Matter ◽  
Tibetan Plateau ◽  
Dissolved Organic Matter ◽  
Melting Rate ◽  
Ion Cyclotron Resonance ◽  
The Tibetan Plateau ◽  
Mountain Glaciers ◽  
Northern Tibetan Plateau ◽  
Fresh Snow ◽  
Northern Edge

AbstractDissolved organic matter (DOM) in mountain glaciers is an important source of carbon for downstream aquatic systems, and its impact is expected to increase due to the increased melting rate of glaciers. We present a comprehensive study of Laohugou glacier no. 12 (LHG) at the northern edge of the Tibetan Plateau to characterize the DOM composition and sources by analyzing surface fresh snow, granular ice samples, and snow pit samples which covered a whole year cycle of 2014/15. Excitation–emission matrix fluorescence spectroscopy analysis of the DOM with parallel factor analysis (EEM-PARAFAC) identified four components, including a microbially humic-like component (C1), two protein-like components (C2 and C3) and a terrestrial humic-like component (C4). The use of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) showed that DOM from all these samples was dominated by CHO and CHON molecular formulas, mainly corresponding to lipids and aliphatic/proteins compounds, reflecting the presence of significant amounts of microbially derived and/or deposited biogenic DOM. The molecular compositions of DOM showed more CHON compounds in granular ice than in fresh snow, likely suggesting newly formed DOM from microbes during snowmelting.

scholarly journals Origin and radiative forcing of black carbon transported to the Himalayas and Tibetan Plateau

2010 ◽  
Vol 10 (9) ◽  
pp. 21615-21651 ◽  
Author(s):  
M. Kopacz ◽  
D. L. Mauzerall ◽  
J. Wang ◽  
E. M. Leibensperger ◽  
D. K. Henze ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Tibetan Plateau ◽  
Black Carbon ◽  
Radiative Forcing ◽  
Middle Eastern ◽  
Central China ◽  
The Tibetan Plateau ◽  
Adjoint Sensitivity ◽  
Snow Albedo ◽  
Northern Tibetan Plateau

Abstract. The remote and high elevation regions of central Asia are influenced by black carbon (BC) emissions from a variety of locations. BC deposition contributes to melting of glaciers and questions exist, of both scientific and policy interest, as to the origin of the BC reaching the glaciers. We use the adjoint of the GEOS-Chem model to identify the location from which BC arriving at a variety of locations in the Himalayas and Tibetan Plateau originates. We then calculate its direct and snow-albedo radiative forcing. We analyze the seasonal variation in the origin of BC using an adjoint sensitivity analysis, which provides a detailed map of the location of emissions that directly contribute to black carbon concentrations at receptor locations. We find that emissions from northern India and central China contribute the majority of BC to the Himalayas, although the precise location varies with season. The Tibetan Plateau receives most BC from western and central China, as well as from India, Nepal, the Middle East, Pakistan and other countries. The magnitude of contribution from each region varies with season and receptor location. We find that sources as varied as African biomass burning and Middle Eastern fossil fuel combustion can significantly contribute to the BC reaching the Himalayas and Tibetan Plateau. We compute radiative forcing in the snow-covered regions and estimate the forcing due to the BC induced snow-albedo effect at about 5–15 W m−2 within the region, an order of magnitude larger than radiative forcing due to the direct effect, and with significant seasonal variation in the northern Tibetan Plateau. Radiative forcing from reduced snow albedo accelerates glacier melting. Our analysis can help inform mitigation efforts to slow the rate of glacial melt by identifying regions that make the largest contributions to BC deposition in the Himalayas and Tibetan Plateau.

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